用网络滤波方法探讨华北地块边界带运动

Network Filtering Method for North China Block Boundary Movement Analysis

介绍了用GPS连续观测资料反演断层运动的方法——网络滤波方法。用此方法探讨了华北地块边界带运动特征,并与发生在边界带附近和地块内部的地震活动及周边强震进行了比较,得出以下初步结论:郯庐大断裂和山西断陷盆地带的滑动量为1mm左右,整体活动水平有减弱的趋势;张家口—渤海断裂带滑动量为0.5mm左右,活动性逐渐增强;秦岭—大别山断裂内滑动量为0.5mm左右,活动性逐渐减弱。在2002年底至2003年底一年左右的时间内,华北地块边界带的滑动速率发生较大幅度的变化,同时,各边界带(秦岭—大别山断裂除外)的地震活动水平在2003年底达到高峰,说明边界带滑动速率急剧变化的结果导致边界带附近地震活动水平的加剧。另外,边界带滑动的特点表明了华北地块构造运动的整体性,推断华北地块的地壳运动可能与来自地球深部的地幔对流有关。

We use the network filtering method, which can invert the movement of faults using GPS continuously observed data, to analyze the characteristics of North China block boundary movement, and compare it with the seismic activity around the boundaries and the strong earthquakes activity around and in the block. The results show that the slip amount is about 1 mm for the Tanlu fault and Shanxi downfaulted zone and the total activity is weakening, and about 0. 5 mm for the Zhangjiakou-Bohai fault zone and with strengthening activity, about 0. 5 mm for the Qinling-Dabieshan fault and with weakening activity. The slip rate in the boundaries of the North China block changed largely from the end of 2002 to the end of 2003, and the seismic activity reached the peak the end of 2003 except the Qinling-Dabieshan fault. This indicates the sharp change of the slip rate around the boundaries results in the sharpening of the seismic activity in the boundaries. In addition, the characteristic of boundary slip shows the coherence with the tectonic movement, of the North China block. It is inferred that the crustal movement in the North China block might be relative to the mantle convection from deep earth.